Excellent combination of mechanical properties and electrical conductivity obtained by minute addition of alloying elements and nanometer scaled Al2O3 in copper alloy.

A superior comprehensive property of Cu–Ni–Si–Al 2 O 3 alloy, including microhardness of 184.4 HV, yield strength of 573 MPa, tensile strength of 607 MPa, and excellent electrical conductivity of 54.9 %IACS, is obtained with the minute addition of alloying elements (∼0.75 wt% Ni and ∼0.20 wt% Si) and nanometer scaled Al 2 O 3 particles. The influence of these Al 2 O 3 particles on the precipitation process and strengthening behaviors has been investigated by the scanning electron microscopy (SEM) equipped with electron-backscattered diffraction (EBSD) and transmission electron microscope (TEM). The results show that the addition of nanometer scaled Al 2 O 3 particles can cause the increase of dislocation density and refinement of the grains during cold deformation and the following aging process. The precipitation kinetics are consequently promoted due to heterogeneous nucleation around the dislocations, sub-grain and grain boundaries and the Al 2 O 3 particles, resulting in the improvement in distribution and refinement of precipitation. The volume fraction and number density of the precipitates are increased, resulting in the simultaneous enhancement of mechanical and electrical properties in the Cu–Ni–Si–Al 2 O 3 alloy. This study provides a significant guidance for the design of precipitation hardening copper alloy, by introducing the precipitation strengthening and dispersion strengthening. [ABSTRACT FROM AUTHOR]